1. Field of the Invention
This invention relates to insulative coatings. Specifically, the present invention relates to an improved lightweight, ablative composition that may be spray applied.
2. Background Information
This invention is closely related to the low density ablative composition disclosed and claimed in U.S. Pat. No. 4,077,921 ('921). In fact, the present invention is an improvement on the '921 patent. Thus, the '921 patent is expressly incorporated by reference as part of the disclosure for the present invention. As stated in column 5, lines 52-55 of the '921 patent, the '921 material can be applied up to a thickness of 0.5 inch without the need for external reinforcement. However, even though the '921 material can be applied up to a thickness of 0.5 inch, the effectiveness of the '921 material is lessened when the coating thickness exceeds 0.25 inch. This reduced effectiveness is attributed to shrinkage cracks, which form from tensile stresses that develop during curing of the '921 material. The present invention overcomes the problem of stress cracking that occurs in the '921 material when the thickness of the '921 coating exceeds 0.25 inch. By controlling stress cracking, the present invention can provide better insulation to those surfaces requiring an ablative insulation coating in excess of 0.25 inch.